Dynamo and regulating means therefor



March 14, 1944. J. A. LAlRD DYNAMO AND REGULATING MEANS THEREFOR Filed Sept. 11, 1942 Patented Mar. 14, 1944 DYNAMO AND BEGULATING MEANS THEREFOR.

John Andrew Laird, Birmingham, England, assignor to Joseph Lucas Limited, Birmingham,

England Application September 11, 1942, Serial No.

In Great Britain October 31, 1941 IClaim.

This invention relates to dynamos, such as those employed on vehicles, and which are subject when in operation to large variations 01 speed and load and which usually operate in conjunction with storage batteries. For the automatic regulation of such a dynamo it is usual to employ vibratory contacts in the fieldwinding system, the contacts being actuated by an electromagnet or electromagnets responsive to the dynamo voltage, or current, or both, and a resistance being arranged in parallel with the contacts or the field-winding to minimise deterioration oi' the active contact surfaces by sparking or arcing. The amount of current which can be utilised in the field-winding is limited by the so-called current-breaking capacity oi the said contacts. The object of the present invention is to enable larger field currents to be satisfactorily employed, and at the same time enable the required automatic control oi the dynamo to be conveniently obtained.

The invention comprises a dynamo and regulator system in which the dynamo is provided with a pair oi field windings, and in which the regulator comprises vibrator contacts in series with one of the windings and a carbon-pile in series with the other winding. the contacts being actuated by an electromagnet responsive to the dynamo voltage or current or both, and the carbon pile being actuated by an electromagnet responsive to the current in the first mentioned neld winding.

In the accompanying sheet of explanatory dia-- gram:

Figure 1 illustrates a dynamo and regulator system embodying the invention.

Figures 2 and 3 illustrate modified details of the system shown in Figure 1.

Figure 4 is a view similar to Figure 1 illustrating a modified form of the invention.

In the diagrams 0. indicates the armature of a dynamo, b a battery used in conjunction with the dynamo, and c the contacts of a cut-out whereby the battery can be connected to the dynamo.

In carrying the invention into effect as shown in Figure 1, I provide the dynamo with two independent field windings d, e, both being connected to the dynamo brushes. The winding d (wihch is usually oi higher resistance than the other winding e) is designed to carry an exciting current such as is capable of being satisiactorily dealt with by vibratory contacts. The winding e is designed to carry a larger current and such as is capable of being satisfactorily dealt with by a carbon pile.

In series with the high resistance winding d are arranged the usual vibratory contacts a which are bridged by the usual resistance 1. The vibratory contacts a are closed by a spring (not shown) and are separated against the action of the spring by an electromagnet h which is responsive to the dynamo voltage. Alternatively the electromagnet may be responsive to the dynamo current or to both the dynamo current and voltage. Instead of a single pair of vibratory contacts as shown in Figure 1, I may use an equivalent known arrangement consisting of two pairs of spring loaded vibratory contacts a 9 arranged in series with the winding d as shown in Figure 2 or 3, the pair 01 contacts g being subject to the action oi an electromagnet 11. responsive to the dynamo voltage and the other pair being subject to the action of a separate electromagnet h responsive to the dynamo current. The two pairs of contacts g,

g may be bridged by either a single resistance j as shown in Figure 2, or separate resistances 1 f as shown in Figure 3.

In series with the low resistance winding e is arranged a carbon pile 4 having associated with one of its ends a pivoted or other arm 4 which tends to slacken or extend the pile under the action of a spring k, and in combination with the pile is arranged an electromagnet m whose.

winding is in series with the high resistance winding d and which serves to oppose the action of the spring.

Instead of arranging a resistance in parallel with the contacts or each pair of contacts as above described, I may arrange a resistance f in parallel with the high resistance winding d as shown in Figure 4. In other'respects the example shown in Figure 4 is similar to that shown in Figure 1 and is indicated by the same reference characters.

When the dynamo conditions in any of the examples above described are such that the contacts 0 or g g are closed the maximum current appropriate to these conditions passes through the high resistance field winding d and this current serves to compress the carbon pile i so causing the maximum current to flow also through the low resistance field winding c. When by separation of the contacts 0, 9 or 9 current in the high resistance field winding d is reduced, the pile i is correspondingly slackened causing a reduction of the cunent in the low resistance field winding e.

A dynamo and regulator system in which the dynamo is provided with a pair 01' field windlngs, and in which the regulator comprises in combination vibratory contacts in series with one of the windings, a carbon pile in series with the other winding, an electromagnet for actuating the contacts in response to a condition associated with the dynamo, and another electromagnet for actuating the carbon pile in response claim as new and desire to secure by Letters 10 to current in the first mentioned field winding.

Patent is:

JOHN ANDREW LAIRD. 

